The 996x Series Gravimetric Calibration System provides for calibration of accelerometers, force sensors, and impact hammers over the low to mid frequency range. For measuring a single value sensitivity, accelerometers and load cells may be "drop" calibrated without a reference sensor, using Earth's gravity instead. Impact hammers are ratio calibrated using a known pendulous mass, a calibrated accelerometer, and Newton's Second Law. The Gravimetric Calibrator is structured with an adjustable frame, vertical and pendulous suspensions, and calibrated test masses. The system is an economical, educational and versatile tool - an important accessory in any structural test laboratory.